Static Random Access Memory (SRAM) is a semiconductor device having the memory cells formed of flip-flop circuits and is operative at high speed.
In semiconductor devices, such as SRAM, etc., gate interconnections, conductor plugs, etc. are laid out in the memory cell parts in very high densities. The gate interconnections, the conductor plugs, etc. are laid out in very high density, whereby the size of the memory cells can be reduced, and the memory capacity can be increased.
Recently, to realize lower costs and larger capacities, the memory cells are required to be more micronized and integrated.
It is required to manufacture SRAM of high reliability at higher yields.
Related reference is as follows:
Japanese Laid-open Patent Publication No. 2002-33389.